.410 loads are not exactly low pressure. But, relatively speaking, the newer powders like ATK .410 and Lil'gun have faster burn rates and operate at relatively higher pressures. Hull lifespan is shorter, too.
296/H110 and 2400 are the standbys and will give less pressure for a given velocity/payload combination - all else equal. 296/H110 is my favorite and will support 1300 fps loadings in high-capacity AAHS hulls.
Another slow powder that is seldom considered b/c of it's loading density is IMR 4227. I haven't seen data for this one for quite some time.
Sam
